P0391 Camshaft Position Sensor ‘B’ Circuit Range/Performance (Bank 2)

COMPONENT LOCATION

GENERAL DESCRIPTION

The Camshaft Position Sensor (CMPS) is a sensor that detects the compression TDC of the NO. 1 cylinder. The CMPS consists of a hall type sensor and a target on the end of the camshaft. When the target triggers the sensor, the sensor voltage is 5V. If not, the sensor voltage is 0V. These CMPS signal is sent to the ECM and the ECM uses the CMPS signal for synchronizing the sequential fuel injectors.

DTC DESCRIPTION

Checking oputput signals from CMP during engine running, if the expected number of cam tooth count is not observed, ECM sets P0391.

DTC DETECTING CONDITION

Item

Detecting Condition

Possible cause

DTC Strategy

Check if CAM sensor is synchronized correctly

1.	Poor connection

2.	Short in harness

3.	electrical noise

4.	Target wheel

5.	CMPS(B2-Exhaust)

ECM

Enable Conditions

Engine running state

Threshold value

Cam tooth count ≠ 6

Diagnosis Time

Continuous

MIL On Condition

3 driving cycles

SPECIFICATION

Item	Specification
Output Voltage(V)	Hi : 5.0V	Low : 0.7V
Airgap(mm)	0.5 ~ 1.5

DIAGNOSTIC CIRCUIT DIAGRAM

SIGNAL WAVEFORM & DATA

Fig.1) Normal waveforms of CMPS

MONITOR GDS DATA

1.	Connect GDS to Data Link Connector(DLC).

IG “ON”.

3.	Select “DTC” button, and then Press “DTC Status” to check DTC’s information from the DTCs menu.

4.	Read “DTC Status” parameter.

Is parameter displayed “Present fault”?

	▶ Go to “Terminal and Connector inspection” procedure.
	▶ Fault is intermittent caused by poor contact in the sensor’s and/or ECM’s connector or was repaired and ECM memory was not cleared. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary

TERMINAL AND CONNECTOR INSPECTION

1.	Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.

2.	Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.

Has a problem been found?

	▶ Repair as necessary and go to “Verification of Vehicle Repair” procedure
	▶ Go to ” Power Circuit Inspection ” procedure.

POWER CIRCUIT INSPECTION

■ Check voltage

1.	IG “OFF” and disconnect CMPS(B2-Exhaust) connector.

IG “ON”.

Measure voltage between power terminal of CMPS(B2-Exhaust) harness connector and chassis ground.

Approx. 5V

Is the measured voltage within specification ?

	▶ Go to “Signal Circuit Inspection” procedure.
	▶ Repair open or short to ground inharness, and go to “Verification of Vehicle Repair” procedure.

SIGNAL CIRCUIT INSPECTION

■ Check short to battery in harness

1.	IG “OFF” and disconnect CMPS(B2-Exhaust) connector.

IG “ON”.

Measure voltage between signal terminal of CMPS(B2-Exhaust) harness connector and chassis ground.

Approx. 5V

Is the measured voltage within specification ?

	▶ Go to “Check short in harness” as follows.
	▶ Go to “Check open in harness” as follows.

■ Check short in harness

1.	IG “OFF” and disconnect CMPS(B2-Exhaust) connector.

Measure resistance between signal and power terminals of CMPS(B2-Exhaust) harness connector.

Infinite

Is the measured resistance within specification?

	▶ Go to “Check short to ground in harness’ as follows.
	▶ Repair short in harness, and go to “Verification of Vehicle Repair” procedure.

■ Check short to ground in harness

1.	IG “OFF” and disconnect CMPS(B2-Exhaust) connector and ECM connector.

Measure resistance between signal terminal of CMPS(B2-Exhaust) harness connector and chassis ground.

Infinite

Is the measured resistance within specification?

	▶ Go to “Component Inspection” procedure.
	▶ Repair short to ground in harness, and go to “Verification of Vehicle Repair” procedure.

■ Check open in harness

1.	IG “OFF” and disconnect CMPS(B2-Exhaust) connector and ECM connector.

Measure resistance between signal terminal of CMPS(B2-Exhaust) harness connector and CMPS(B2-Exhaust) signal terminal of ECM harness connector.

Below 1Ω

Is the measured resistance within specification?

	▶ Go to “Ground Circuit Inspection” procedure.
	▶ Repair open in harness, and go to “Verification of Vehicle Repair” procedure.

GROUND CIRCUIT INSPECTION

■ Check open in harness

1.	IG “OFF” and disconnect CMPS(B2-Exhaust) connector and then IG “ON”.

2.	Measure voltage between signal terminal of CMPS(B2-Exhaust) harness connector and chassis ground.(Measurement “A”)

Measure voltage between signal and ground terminals of CMPS(B2-Exhaust) harness connector.(Measurement “B”)

Voltage difference between measurement “A” and “B” is below 200mV.

Is the measured voltage within specification ?

	▶ Go to “Component Inspection” procedure.
	▶ Repair contact resistance or open in harness

COMPONENT INSPECTION

■ Check CMPS

1.	IG “OFF” and connect GDS.

2.	ENG “ON” and Measure signal waveform at signal terminal of CMPS. Reference signal waveform : Fig. 1) Normal waveform of CMPS1 & 2 at idle.

Is the measured signal waveform normal?

▶ Substitute with a known – good ECM and check for proper operation. If the problem is corrected, replace ECM and go to “Verification of Vehicle Repair” procedure.

There is a memory reset function on GDS that can erase optional parts automatically detected and memorized by ECM. Before or after testing ECM on the vehicle, use this function to reuse the ECM on the others

▶ Substitute with a known – good CMPS and check for proper operation. If the problem is corrected, replace CMPS

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